Who care about Facebook and Twitter? Giving hints JUST there is insulting for your players who do not use those. Not to mention that you basically say that only those players count...
Are there any hints about it in-game? Epilogues provide hints occasionally, but again is there any hint or clue in game about how to get final part of Loser quest?
There's no need to. If people want to find out they will look on twitter and facebook. If you don't want to, that's fine. But don't generalize.
When hints were given on twitter about the last part of the looser quest series, there was a thread in the saloon where people discussed the hints trying to figure out how to get it. So if you are lazy enough to read the forum as well, then to bad for you.
And yes, not everybody reads the forum reason why people like me who do read the forum ask town members if they wish to know and share the info.
I don't care if you don't want to do any efforts to find out stuff. It is not put in game for a reason: not to make it to easy. The gun was easy to get anyway, the requirements (once you know them) are not hard to fulfill, so at least the devs made it hard to find out.
And when you will have a game made and ran by yourself and you will be able to make everybody happy, then I will take into consideration your views. Until then, we will have happy people and ranting people around. The developers are only human, they can't satisfy everybody, but they do a good job satisfying the majority.